Timing Question

You also mention you "changed the spring and opened the slots to bring the timing in later", opening the mechanical weight slots only allows the advance so swing out further and therefor adding even more timing.

I would try to set the initial timing to where the manifold vacuum is the highest. Set the idle rpm to around 700-750, make sure the vacuum advance is disconnected and all vacuum ports are blocked off. Hook up a vacuum gauge to a manifold source or hook it up to the carb but make sure it is hooked up below the throttle blades (manifold not ported).

Loosen the distributor and move it to where you see an increase in manifold vacuum (you might have to retard it if you have the initial set too high). While moving the distributor the rpm will also change. If the idle rpm changes by more than 50 rpm set it back to 700-750.

You'll notice the vacuum will climb until it reaches its max potential, this is usually where the cam wants the initial timing to be. (again make sure you get this reading at 700-750rpm). Check with the timing gun what the initial now is.

Depending on this number you have to either make the slots longer or limit the mechanical timing slots. Most likely they need to be limited since you are running a non-stock cam. You might also want to bring the springs in the distributor back to stock before you start with any of this.

Sorry about the long write up, but hope it helps you out some.